christoph/lecture-operating-system-development
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fix bufferedcga bug where buffer was used before init

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This commit is contained in:
churl
2022-05-10 00:20:25 +02:00
parent 15515269a1
commit b860c82d87
2 changed files with 37 additions and 25 deletions
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54
c_os/devices/BufferedCGA.cc
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@ -10,12 +10,16 @@ void BufferedCGA::init() {
}
void BufferedCGA::displaypage() {
if (this->current_page == 0) {
// Use pagebuffer
this->scrollback_buffer->copy_page_from_pagebuffer((cga_page_t*)CGA_START);
if (this->initialized) {
if (this->current_page == 0) {
// Use pagebuffer
this->scrollback_buffer->copy_page_from_pagebuffer((cga_page_t*)CGA_START);
} else {
// Use scrollback
this->scrollback_buffer->copy_page_from_buffer((cga_line_t*)CGA_START, this->current_page - 1);
}
} else {
// Use scrollback
this->scrollback_buffer->copy_page_from_buffer((cga_line_t*)CGA_START, this->current_page - 1);
this->print("ScrollbackBuffer not initialized\n\n", 34);
}
}
@ -51,25 +55,33 @@ void BufferedCGA::clear() {
}
}
unsigned int BufferedCGA::scroll_page_backward() {
// If this is the first scrollback we have to save the current screen content
if (this->current_page == 0) {
this->scrollback_buffer->copy_page_to_pagebuffer((cga_page_t*)CGA_START);
}
void BufferedCGA::scroll_page_backward() {
if (this->initialized) {
// current_page can be equal to scrollback_buffer->pages
// as we have a separate pagebuffer for the current screen content
if (this->current_page < this->scrollback_buffer->pages) {
this->current_page = this->current_page + 1;
// If this is the first scrollback we have to save the current screen content
if (this->current_page == 0) {
this->scrollback_buffer->copy_page_to_pagebuffer((cga_page_t*)CGA_START);
}
// current_page can be equal to scrollback_buffer->pages
// as we have a separate pagebuffer for the current screen content
if (this->current_page < this->scrollback_buffer->pages) {
this->current_page = this->current_page + 1;
}
this->displaypage();
} else {
this->print("ScrollbackBuffer not initialized\n\n", 34);
}
this->displaypage();
return this->current_page;
}
unsigned int BufferedCGA::scroll_page_forward() {
if (this->current_page > 0) {
this->current_page = this->current_page - 1;
void BufferedCGA::scroll_page_forward() {
if (this->initialized) {
if (this->current_page > 0) {
this->current_page = this->current_page - 1;
}
this->displaypage();
} else {
this->print("ScrollbackBuffer not initialized\n\n", 34);
}
this->displaypage();
return this->current_page;
}